U.S. patent number 11,383,489 [Application Number 15/706,817] was granted by the patent office on 2022-07-12 for package comprising a sealed contact area including a nonwoven having a bonded surface with an embossed impression pattern.
This patent grant is currently assigned to DUPONT SAFETY & CONSTRUCTION, INC.. The grantee listed for this patent is DUPONT SAFETY & CONSTRUCTION, INC.. Invention is credited to Richard Alan Jackson.
United States Patent |
11,383,489 |
Jackson |
July 12, 2022 |
Package comprising a sealed contact area including a nonwoven
having a bonded surface with an embossed impression pattern
Abstract
This invention relates to a package for providing an enclosed
interior environment capable of being sterilized and a gas
permeable fibrous nonwoven sheet structure useful in such
structure, wherein the nonwoven sheet structure has at least one
surface having a pre-sealed, embossed impression pattern; and a
particle barrier penetration of below 10%, a Gurley Hill Porosity
of 40 seconds or less, and a moisture vapor transport rate of 3500
g/m.sup.2/day or greater.
Inventors: |
Jackson; Richard Alan (Glen
Allen, VA) |
Applicant: |
Name |
City |
State |
Country |
Type |
DUPONT SAFETY & CONSTRUCTION, INC. |
Wilmington |
DE |
US |
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Assignee: |
DUPONT SAFETY & CONSTRUCTION,
INC. (Wilmington, DE)
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Family
ID: |
1000006427246 |
Appl.
No.: |
15/706,817 |
Filed: |
September 18, 2017 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180099483 A1 |
Apr 12, 2018 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62406547 |
Oct 11, 2016 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B32B
9/047 (20130101); B32B 3/30 (20130101); D21H
27/02 (20130101); B32B 27/34 (20130101); B32B
7/12 (20130101); B32B 27/12 (20130101); B32B
27/36 (20130101); B32B 7/06 (20130101); B32B
27/08 (20130101); B32B 27/306 (20130101); B32B
5/022 (20130101); B32B 27/32 (20130101); B32B
2439/46 (20130101); B32B 2307/75 (20130101); B32B
2439/40 (20130101); B32B 2307/724 (20130101); B32B
2262/0253 (20130101); B32B 2305/02 (20130101); B32B
2439/80 (20130101); B32B 2323/04 (20130101) |
Current International
Class: |
B32B
9/04 (20060101); B32B 27/36 (20060101); B32B
27/12 (20060101); B32B 27/32 (20060101); B32B
7/06 (20190101); B32B 27/08 (20060101); D21H
27/02 (20060101); B32B 3/30 (20060101); B32B
5/02 (20060101); B32B 7/12 (20060101); B32B
27/34 (20060101); B32B 27/30 (20060101) |
Field of
Search: |
;264/310,284 ;604/408
;428/36.6,36.4,35.2,230,35.7 ;206/438,484.3,532,277,439,363,204
;383/102,103 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2000510198 |
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Aug 2000 |
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JP |
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2017522210 |
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Aug 2017 |
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JP |
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9740224 |
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Oct 1997 |
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WO |
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9740224 |
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Oct 1997 |
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WO |
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Other References
International Search Report, dated Nov. 29, 2017, for International
Application No. PCT/US2017/051323, International Filing Date Sep.
13, 2017; ISA/European Patent Office; Authorized Officer,
Jena-Francois Maxet. cited by applicant.
|
Primary Examiner: Salvatore; Lynda
Claims
What is claimed is:
1. A package for providing an enclosed interior environment capable
of being sterilized, the package consisting of a gas permeable
fibrous nonwoven sheet consisting of polyethylene plexifilaments,
polymeric tie layer, and package substrate, the nonwoven sheet
having a first surface and a second surface; the enclosed interior
environment being formed by sealing an area of contact between the
first surface of the nonwoven sheet and the package substrate, the
sealed area of contact being formed by the polymeric tie layer,
wherein the first surface of the nonwoven sheet is pre-bonded with
an embossed impression pattern at least within the sealed area of
contact, and wherein the second surface of the nonwoven sheet is
free of any embossed pattern, and wherein the sealed area of
contact being formed by the polymeric tie layer and the first
surface pre-bonded with an embossed impression pattern passes the
dye penetration test per ASTM F1929-12, and wherein the first
surface pre-bonded with an embossed impression pattern, when
compared to a non-embossed surface, provides a reduction in visible
fiber tears of at least 25 percent after the sealed area of contact
is opened by peeling the sheet from the polymeric tie layer.
2. The package of claim 1 wherein the polymeric tie layer is
integral with the package substrate.
3. The package of claim 1 wherein the polymeric tie layer and
package substrate are combined in a film.
4. A fibrous nonwoven sheet suitable for use in a sterile package
made by sealing the nonwoven sheet to a package substrate via a
polymer tie layer, wherein the sterile package is later opened by
peeling the sheet from the polymeric tie layer, the sheet being gas
permeable and having a first surface and a second surface and
consisting of polyethylene plexifilaments; the first surface being
bonded with an embossed impression pattern and the second surface
being capable of accepting printing, wherein the second surface of
the nonwoven sheet is free of any embossed pattern; the sheet
having a particle barrier penetration of below 10%, a Gurley Hill
Porosity of 40 seconds or less, and a moisture vapor transport rate
of 3500 g/m.sup.2/day or greater, wherein when a sealed area of
contact is formed between the first surface pre-bonded with an
embossed impression pattern and the polymeric tie layer of the
package substrate, the sealed area of contact passes the dye
penetration test per ASTM F1929-12, and wherein the first surface
pre-bonded with an embossed impression pattern, when compared to a
non-embossed surface, provides a reduction in visible fiber tears
of at least 25 percent after the sealed area of contact is opened
by peeling the sheet from the polymeric tie layer.
5. The fibrous nonwoven sheet of claim 4 having a Gurley Hill
Porosity of 10 seconds or less.
6. The fibrous nonwoven sheet of claim 4 having a moisture vapor
transport rate of 7500 g/m.sup.2/day or greater.
7. The fibrous nonwoven sheet of claim 6 having a moisture vapor
transport rate of 9000 g/m.sup.2/day or greater.
8. The package of claim 1 wherein the fibrous nonwoven sheet having
at least one surface prebonded with an embossed impression pattern,
when compared to a non-embossed structure, provides an improved
seal strength as measured by both average mean load and average
peak load.
9. The fibrous nonwoven sheet of claim 4 wherein the at least one
surface prebonded with an embossed impression pattern, when
compared to a non-embossed structure, provides an improved seal
strength as measured by both average mean load and average peak
load.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates to improved packages for providing an
enclosed interior environment capable of being sterilized, and
gas-permeable fibrous nonwoven sheet structures suitable for use
therein.
Description of Related Art
U.S. Pat. No. 6,034,008 to Lim et al. discloses a sheet material
suitable for use in filtration and sterile packaging that has
strength, weight and barrier properties at least equivalent to that
of the TYVEK.RTM. spunbonded olefin nonwoven sheet material that
has been traditionally used for such applications, but that also
has significantly improved air and liquid permeability.
In particular, Lim et al. discloses a whole surface bonded "hard
structure" product that has the feel of slick paper that is used
commonly in a number of applications, including sterile packaging;
and a point bonded and softened "soft structure" product with a
more fabric-like feel for apparel applications.
As Lim et al. discloses, it is thought that the full surface
bonding of a "hard structure" flash-spun sheet product causes the
high surface area plexifilamentary fibers of the sheet to shrink,
which in turn causes the pores between the fibers to open up.
Accordingly, "hard structure" sheet products generally have higher
moisture vapor transmission rates and higher hydrostatic head
values as compared to "soft structure" sheet products. This more
permeable material has been found to have great utility in sterile
packaging materials where increased permeability permits the
materials to perform their function in a more efficient manner.
Fibrous nonwoven sheets are useful in packages that can be
sterilized because they allow manufacturers to first package items
and then sterilize the items in the packages, using gases such as
steam, ethylene oxide, or some combination thereof. The sterilizing
gas is able to penetrate the package through the fibrous nonwoven
sheets to sterilize the enclosed interior of the package. Suitable
fibrous nonwoven sheets also provide a barrier to contaminants to
prevent the sterilized packaged items from being contaminated prior
to the package being opened.
It is not unusual for the sterilized packages to be opened in a
sterilized environment, and one desirable feature of the fibrous
nonwoven sheet is that it be peelable from the package without
excessive tear of the nonwoven sheet surface when the sheet is
removed. It is believed by some that the rupture of the surface of
the nonwoven sheet during peeling, the fiber tear, could possibly
contaminate the sterilized environment in which the package is
opened.
Since most sterilized packages are used in health-related settings
like operating rooms, any improvement that helps prevent or reduces
any possible contamination is desirable. In packaging, in
particular any improvement in the peel performance of the fibrous
nonwoven structure is greatly desired.
BRIEF SUMMARY OF THE INVENTION
This invention relates to a package for providing an enclosed
interior environment capable of being sterilized, the package
comprising a gas permeable fibrous nonwoven sheet structure,
polymeric tie layer, and package substrate; the nonwoven sheet
structure having a first surface and a second surface; the enclosed
interior environment being formed by sealing an area of contact
between the first surface of the nonwoven sheet structure and the
package structure, the sealed area of contact being formed by the
polymeric tie layer; wherein the first surface of the nonwoven
sheet structure is pre-bonded with an embossed impression pattern
at least within the sealed area of contact.
This invention also relates to a fibrous nonwoven sheet structure
suitable for use in sterile packaging, the sheet structure being
gas permeable and having a first surface and a second surface; the
first surface being bonded with an embossed impression pattern and
the second surface being capable of accepting printing; the sheet
structure having a particle barrier penetration of below 10%, a
Gurley Hill Porosity of 40 seconds or less, and a moisture vapor
transport rate of 3500 g/m.sup.2/day or greater.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are illustrations of some embossed impression
patterns.
FIGS. 3 and 4 are illustrations of some packaging substrates
showing the area of sealing.
FIG. 5 is an Illustration of the location of the 4 samples for the
determination of the seal strength of a package.
DETAILED DESCRIPTION OF THE INVENTION
This invention relates to a package for providing an enclosed
interior environment capable of being sterilized and a gas
permeable fibrous nonwoven sheet structure useful in such
structure, wherein the nonwoven sheet structure has at least one
surface being prebonded with an embossed impression pattern and
having a particle barrier penetration of below 10%, a Gurley Hill
Porosity of 40 seconds or less, and a moisture vapor transport rate
of 3500 g/m.sup.2/day or greater.
Surprisingly, it has been found that a nonwoven sheet structure
having a bonded surface with an embossed impression pattern can be
used in a sealed package having an interior environment capable of
being sterilized. It is surprising in that (1) an embossed nonwoven
surface can provide a good seal to the package structure, and also
(2) the resulting package has a superior level of peel performance
when the package is opened, better in many instances than smooth
surface bonded sheets.
It is desirable that any package utilized and opened in a sterile
environment have a "clean peel" or provide an "aseptic
peel/presentation", terms used by the medical industry to refer to
the requirement that the package can be opened and the contents
presented to the sterile environment without risk of contamination.
As used herein, this superior opening performance is determined by
the use of a "fiber tear" criterion. Surprisingly, the use of a
nonwoven sheet structure having at least one surface being
prebonded with an embossed impression pattern, in contact with a
polymeric tie layer, can provide packages that have a clean peel
and have very low fiber tear, or are actually fiber tear free.
Even more remarkable is that this superior level of peel
performance is achieved without any additional coating layers on
the fibrous nonwoven sheet structure. The use of nonwoven coatings
can provide an improved peel, but the simple use of such coatings
can generate other loose particles that risk the aseptic
presentation.
The package for providing an enclosed interior environment capable
of being sterilized comprises a gas permeable fibrous nonwoven
sheet structure, polymeric tie layer, and package substrate.
The packaging substrate can be any material that forms a flexible
or semi-rigid package, such as packaging in the form of a sachet, a
bag, a sheath, or a blister pack. The package including the
packaging substrate generally serves to protect the package item
and in the case of sterile packaging helps maintain the packaged
item in a non-contaminated state until ready for use. In one
practical application, the item to be packaged is put into the
packaging substrate, and then it is sealed, using a polymeric tie
layer and a gas permeable fibrous nonwoven sheet structure to form
the enclosed environment. Then if desired the package with the
enclosed item can be sterilized using a suitable sterilizing gas.
In some embodiments the packaging substrate comprises polyamides
(especially nylons), polypropylene, polyesters (especially
polyethylene terephthalate) and any combination thereof.
The package includes a polymeric tie layer to seal an area of
contact between the nonwoven sheet structure and the package
structure. The polymeric tie layer is preferably any flexible or
semi-rigid film that is compatible with both the packaging
substrate and the nonwoven sheet structure and will suitably seal
the nonwoven sheet structure to the packaging substrate. By
compatible with, it is meant the polymeric tie layer does not
adversely react with either the nonwoven sheet or the packaging
substrate and has a suitable shelf life, maintaining a package
sealed until its intended use. In some preferred embodiments, the
polymeric tie layer is integral with the packaging substrate. As
shown in FIGS. 3 and 4, the seal areas 15 and 17 illustrate one
embodiment of the area where the polymeric tie layer forms a sealed
area of contact, where the package substrate the fibrous nonwoven
sheet structure would contact
The polymeric tie layer is preferably in the form of a film. The
composition of the polymeric tie layer can comprise compositions
including such things as, for example, polyethylene, including
low-density polyethylene, ethylene vinyl acetate, and any
combination thereof.
In some preferred embodiments, the polymeric tie layer and package
substrate are integral. In some embodiments they are combined in
the same film. In this case, as used herein, the packaging
substrate is defined as a "structural material" and that structural
material is integrally combined with a polymer useful as a
polymeric tie layer in the film. For example, some useful
structural materials include polyamides (especially nylons),
polypropylene, polyesters (especially polyethylene terephthalate)
and any combination thereof. Especially desired structural
material/polymeric tie layer combinations that can be used when the
package substrate and polymeric tie layer are integral include
polyimide/polyethylene, polyester/polyethylene,
polypropylene/polyethylene, polypropylene/ethylene vinyl acetate,
polyimide-polypropylene/polyethylene, and the like.
The fibrous nonwoven sheet structure is gas permeable, meaning that
sterilizing gases such as ethylene oxide and/or steam can pass
through the sheet without the use of excessive pressure. In
particular the fibrous nonwoven sheet structure has a Gurley
Porosity (also known as Gurley-Hill porosity) of 40 seconds or
less. This property is a measure of how long it takes a volume of
gas to pass through an area of material wherein a certain pressure
gradient exists; therefore, lower numbers mean the material is more
gas permeable, and higher numbers mean the material is less
permeable. In some embodiments, the fibrous nonwoven sheet
structure has a Gurley Porosity of 10 seconds or less. In some
embodiments, the fibrous nonwoven sheet structure has a Gurley
Porosity of 5 seconds or less, and some most preferred embodiments
the fibrous nonwoven sheet structure has a Gurley Porosity of 3
seconds or less.
Another indicator of permeability is the measured value of moisture
vapor transport, with higher values being more permeable. This is
particularly important when steam is used as part of the
sterilizing process. The fibrous nonwoven sheet structure has a
moisture vapor transport rate of at least 3500 g/m.sup.2/day or
greater. In some preferred embodiments, the fibrous nonwoven sheet
structure has a moisture vapor transport rate of at least 7500
g/m.sup.2/day or greater. In some other embodiments, the fibrous
nonwoven sheet structure has a moisture vapor transport rate of at
least 9000 g/m.sup.2/day or greater. Preferably the fibrous
nonwoven sheet structure is uncoated, allowing for a more permeable
sheet structure. The use of coatings for improved adhesion tend to
close the surface of the nonwoven sheet structure, reducing the
rate at which the sterilizing gas can pass through the
structure.
The fibrous nonwoven sheet structure has a first surface and a
second surface with the first surface being bonded with an embossed
impression pattern. As used herein the phrase "being bonded with an
embossed impression pattern" means the surface has at least two
characteristics, the first being the fibrous material on the
surface has been "bonded", meaning that the fibrous material has
been substantially consolidated and stabilized by from the heat and
pressure provided to the sheet from heated sources such as rolls;
and that, additionally, the surface has an embossed impression
pattern that leaves the surface with a visual texture. As used
herein, the use of the words "is pre-bonded" is meant the fibrous
nonwoven sheet structure is embossed prior to being incorporated
into any package.
In one embodiment, the embossed impression pattern in the sheet is
provided by calendering the nonwoven sheet in the nip between a
heated metal roll and elastomeric backup roll, the metal roll being
provided with a pattern of raised areas or bosses extending
radially outward from the surface of the roll. In some preferred
embodiments, the raised areas or bosses extend 0.008 to 0.020
inches (0.20 to 0.50 mm) from the surface of the remainder of the
roll. In some other embodiments, the raised areas or bosses can
have a width of 0.005 to 0.025 inches (0.12 to 0.64 mm). In some
preferred embodiments, the width of the raised areas or bosses can
be 0.005 to 0.015 inches (0.12 to 0.38 mm).
When the fibrous nonwoven sheet is pressed in the nip between the
heated metal roll having the raised areas or bosses and the
elastomeric backup roll, the nonwoven sheet is left with an
embossed impression pattern having a depth essentially equivalent
to the dimensions of the bosses. FIGS. 1 and 2 provide
illustrations of two potentially useful and desired embossed
impression patterns, with FIG. 1 referred to as a linen pattern and
FIG. 2 referred to as a dogbone pattern.
One preferred method of embossing the nonwoven sheet is thermally
bonding the sheet on a modified machine similar to that described
in FIG. 2 of U.S. Pat. No. 5,972,147 to Janis. In the pre-heating
section of that modified machine, each of the sides of the nonwoven
being bonded are put in contact with a plurality of preheat rolls.
In some preferred embodiments for the embossed nonwoven sheet
described herein, the Janis machine is modified such that there are
four heating rolls in this section, operating at temperatures
sufficient to essentially provide generous surface bonding of the
sheet. The temperatures will depend on the melting point of the
material being bonded. After the preheat rolls, the sheet passes
through preferably only one of the multiple embosser stations shown
to apply an embosser pattern to preferably only one surface of the
sheet. On each embosser station there is an embosser roll that can
be pressed onto a back-up roll to form a nip. The pressure between
the embosser and back-up roll is expressed in pounds per linear
inch (pli). The back-up roll is typically covered with an
elastomeric covering and is internally cooled by a re-circulation
cooling media. The nonwoven sheet is subsequently transferred to a
plurality of cooling rolls where the temperature of the sheet
material is reduced, and then wound up into a roll.
The use of multiple preheating rolls operating at high temperatures
not only helps bond the first surface of the nonwoven to be
embossed, but also provides an opposite second surface that is also
a bonded. This second surface is preferably capable of accepting
printing. Further is it preferred that the second surface have a
smooth surface free of any embossing for the best printing
performance. Many packages require very specific bar codes and
other delicate and small indicia, which requires a very uniform and
flat surface free of the texture provided by embossing.
Alternatively, the sheet can be first surface bonded, wound up on a
roll, and then subsequently unwound and embossed on one side to
provide the first surface being bonded with an embossed impression
pattern. Other embossing processes are possible, as long as they
provide the fibrous nonwoven sheet having at least a first surface
that is bonded with an embossed impression pattern. Preferably the
process provides a second surface being capable of accepting
printing. Preferably the second surface is uniform and free of any
embossed pattern.
In some embodiments, the fibrous nonwoven sheet structure has good
barrier to contaminates and has adequate durability to withstand
general handling without damage or contamination to the packaged
contents. Therefore, the fibrous nonwoven sheet structure having an
embossed impression pattern preferably has a particle barrier
penetration of below 10%, as determined with a TSI 8130 equipment.
It is believed that his particle barrier test is useful in
determining the degree of barrier the sheet provides to
contaminants, and the contaminants could include those that might
be bacterial in nature. Further, the fibrous nonwoven sheet
structure having an embossed impression pattern preferably has a
Mullen burst strength above 500 kPa and measured Elmendorf tear
performance above 2 N/m.
The fibrous nonwoven sheet structure includes nonwoven fabrics that
can provide a stabilized surface with an embossed impression
pattern for use in contact with the polymeric tie layer on the
package. Such nonwoven sheet structures can include flash spun
nonwoven sheet structures, spunbonded nonwovens, meltblown sheets,
electro-blown sheets and any combination thereof. By fibrous, it is
meant the material in the nonwoven sheet has some fibrous nature.
This fibrous nature can be provided by such things as staple
fibers, continuous or semi-continuous fibers, and/or
plexifilamentary fibrous structures. The fibrous material can
comprise a single material or a multitude of materials, either as a
combination of different fibers or as a combination of similar
fibers each comprised of different materials. The term "nonwoven"
means the planar sheet structure comprises at least one web of
randomly distributed fibrous material as opposed to woven or
knitted fabrics, which are made by interwoven yarns or interlocked
yarn loops. In some preferred embodiments the fibrous material in
the nonwoven sheet is a synthetic polymer; in some embodiment the
synthetic polymer is a thermoplastic polymer. In some preferred
embodiments the fibrous material in the nonwoven sheet structure is
free of added binder; that is, the fibrous material is bound in the
sheet by melting of fibrous cross points in the sheet structure
without additional binder compounds being added to the sheet.
In some embodiments the fibrous nonwoven sheet structure has a
basis weight of less than 55 grams per square meter. In some more
preferred embodiments the fibrous nonwoven sheet structure has a
basis weight is less than 50 grams per square meter; and in some
most preferred embodiments the fibrous nonwoven sheet structure has
a basis weight of less than 45 grams per square meter.
The preferred fibrous material in the fibrous nonwoven sheet
structure is plexifilamentary. The terms plexifilamentary and
plexifilament as used herein refers to a three-dimensional integral
network of a multitude of thin, ribbon-like, film-fibrils of random
length and with a mean fibril thickness of less than about 4
micrometers and a median width of less than about 25 micrometers.
In plexifilamentary structures, the film-fibrils are generally
coextensively aligned with the longitudinal axis of the structure
and they intermittently unite and separate at irregular intervals
in various places throughout the length, width and thickness of the
structure to form a continuous three-dimensional network. Such
structures are described in further detail in U.S. Pat. Nos.
3,081,519 and 3,227,794.
The preferred method of making a fibrous nonwoven sheet structure
having plexifilamentary fibrous material is by flash spinning. The
resulting fibrous nonwoven sheet structure containing
plexifilamentary film-fibril elements is also known as a flash spun
plexifilamentary sheet.
As such, the preferred fibrous nonwoven sheets suitable for further
bonding and embossing can be made using the general flash spinning
technology as described in U.S. Pat. No. 3,227,794 to Anderson and
U.S. Pat. No. 3,860,369 to Brethauer et al. Especially preferred
fibrous nonwoven sheets suitable for further bonding and embossing
can be made using a spin solution comprising high density
polyethylene and a hydrocarbon spin agent as for example in U.S.
Pat. Nos. 6,010,970; 7,338,916; 8,048,513; and 6,034,008.
Preferably, the fibrous nonwoven sheets suitable for further
bonding having improved permeability and barrier strength
properties by flash spinning the sheet from a hydrocarbon-based
spin solution comprising of between 12% and 20% by weight
polyethylene and maintained at a temperature of above 180.degree.
C. prior to flashing; in some embodiments, the temperature is
between 185.degree. to 195.degree. C. prior to flashing.
The fibrous material in the nonwoven sheet is preferably a
polyolefin. Polyolefins can include polyethylene, polypropylene,
polymethylpentene, polybutylene, and combinations thereof.
Preferably the polyolefin is polyethylene. Polyethylene includes
not only homopolymer of ethylene, but also copolymers wherein at
least 85% of the recurring units arise from ethylene. A preferred
polyethylene is linear high density polyethylene having an upper
limit of melting range of about 130.0 to 137.0.degree. C., a
density in the range of 0.94 to 0.98 g/cm.sup.3 and a melt index
(as defined by ASTM D-1238-57T, Condition E) of between 0.1 to 100,
preferably between 0.1 and 4. Polypropylene includes not only
homopolymer of propylene but also copolymers wherein at least 85%
of the recurring units arise from propylene units.
The package comprising a gas permeable fibrous nonwoven sheet
structure, polymeric tie layer, and package substrate provides an
enclosed interior environment capable of being sterilized. The
enclosed environment is formed by sealing an area of contact
between the first surface of the nonwoven, that is prebonded with
an embossed impression pattern, and the package structure, with the
polymeric tie layer.
In some embodiments, the package can be a type of pouch made from a
film having a cavity for the material to be packaged, with the
fibrous nonwoven sheet sealing the package. In this embodiment, it
is preferred that the polymeric tie layer be integral to the film
of the pouch, the tie layer being essentially the film exposed on
the interior of the pouch such that comes in contact with the
fibrous nonwoven sheet.
Alternatively, in some embodiments, the package can be a type of
blister package, with the package substrate having thermoformed
blister cavities for the material to be packaged and the fibrous
nonwoven sheet structure providing the lidding for the package.
Again, in a preferred embodiment, the polymeric tie layer is
integral, being the inner surface of the thermoformed cavities and
along with the lip of the package in contact with the fibrous
nonwoven sheet sealing the cavities.
Plan views of two package substrates having cavities 16 and 18 are
shown in FIGS. 3 and 4, respectively, the package substrates have
sealing areas 15 and 17, respectively, that surround the cavities.
When the cavities are sealed, the fibrous nonwoven sheet structure
covers both the sealing areas and the cavities. The polymeric tie
layer is disposed in the sealing area, positioned between the
package substrate including the cavities and the fibrous nonwoven
sheet material. The polymeric tie layer can be integral to the
packaging substrate, which is preferred.
In some embodiments, the package is manufactured by forming the
desired package substrate with the polymeric tie layer, filling the
cavities with the material to be packaged, and then applying the
nonwoven sheet structure pre-bonded with an embossed impression
pattern, the embossed impression pattern being in contact with the
polymeric tie layer, and then sealed. In some embodiments the
nonwoven sheet structure can be a lidding component for a blister
pack. The package is then sealed either by heat, pressure or a
combination of both.
In some embodiments, the components are heat sealed, typically
using a heated platen. While the cavity containing the item to be
packaged is fully sealed, if desired some other areas on the
package need not be fully sealed to provide a starting point for
peeling off the fibrous nonwoven sheet structure prior to removing
the product. If the fibrous nonwoven sheet structure is not
pre-printed prior to sealing, the nonwoven sheet structure can be
printed just before or after heat sealing.
While the preferred package embodiments are either pouches or
blister-type packages it is understood any flexible of semi-rigid
package, including such packages in the form of a sachet, a bag, or
a sheath could use the fibrous nonwoven sheet structure prebonded
with an embossed impression pattern as a gas-permeable feature.
The formed package has an enclosed interior environment for an item
to be packaged, formed by sealing an area of contact between the
first surface of a nonwoven sheet structure and the package
substrate with the sealed area of contact being the polymeric tie
layer, and the first surface of the nonwoven sheet structure being
pre-bonded with an embossed impression pattern at least within the
sealed area of contact. In some embodiments, the formed package has
an enclosed interior environment including an item packaged by the
enclosed environment, the enclosed environment formed by sealing an
area of contact between the first surface of a nonwoven sheet
structure and the package substrate with the sealed area of contact
being the polymeric tie layer, and the first surface of the
nonwoven sheet structure being pre-bonded with an embossed
impression pattern at least within the sealed area of contact.
In some embodiments the formed package is a heat-sealed peelable
package. As defined herein, the phrase "peelable package" means the
sheet structure is sealed to the package with a "peelable seal". As
defined herein, the phrase "peelable seal" means the sheet
structure, having been sealed to the package, has an average peak
load seal strength that is at least 0.5 pounds force per inch up to
a maximum of 4 pounds force per inch or less. This means the sheet
structure can be removed from the sealed package by hand, by
exerting at least 0.5 pounds force per inch of seal and at most 4
pounds force per inch of seal. In some preferred embodiments the
maximum average peak load seal strength is 3 pounds force per inch
or less. In addition, the fibrous nonwoven sheet structure, because
it has at least one surface being bonded with an embossed
impression pattern, makes the surface bonded embossed impression
pattern capable of making a "peelable seal" with the package.
One measure of seal integrity is characterized by the dye
penetration test as described in ASTM F1929-12. Surprisingly, the
packages made with a nonwoven sheet structure that is pre-bonded
with an embossed impression pattern, and attached to the polymeric
tie layer by the embossed surface in the seal area was found to
have no negative impact on the dye penetration test.
The formed package has outstanding sealing and peeling properties.
Surprisingly, the use of a fibrous nonwoven sheet structure having
at least one surface being prebonded with an embossed impression
pattern, in contact with a polymeric tie layer, can provide
packages that have a clean peel and have very low fiber tear, or
are actually fiber tear free. Surprisingly, when the surface of the
nonwoven sheet with the embossing pattern is sealed to the film,
the peel characteristics are improved.
The improved peel characteristics are shown by both a reduction in
the percentage of packages that show fiber tear and/or a reduction
in the severity of the fiber tear. Specifically, it has been found
that when compared to non-embossed materials, the fibrous nonwoven
sheet structure having at least one surface with an embossed
impression pattern has a significant reduction in the packages that
do not provide a clean peel. In particular it has been found that
the use of an embossed sheet structure, when compared to a
non-embossed structure, can provide at least a 25 percent reduction
in packages with visual fiber tears, preferably at least a 30
percent reduction, or even higher.
In addition, it has been found that the seal strength, as measured
by both average mean load and average peak load, is improved over
the use of non-embossed fibrous nonwoven sheet structures. In other
words, both the strength of the seal, and the quality of the peel
are both improved by the use of an embossed surface on the face of
the fibrous nonwoven sheet structure in contact with the polymeric
tie layer.
Test Methods Basis weight. The basis weight is measured according
to ASTM D3776 (2009).
Gurley Hill Porosity (or just "Gurley Porosity"; the phrases used
interchangeably herein) is a measure of the permeability of the
sheet material for gaseous materials. In particular, it is a
measure of how long it takes a volume of gas to pass through an
area of material wherein a certain pressure gradient exists.
Gurley-Hill porosity is measured in accordance with TAPPI T-460
OM-88 using a Lorentzen & Wettre Model SE 166 or 516 from
Lorentzen & Wettre, Kista, Sweden. This test measures the time
required for 100 cubic centimeters of air to be pushed through a
28.7 mm diameter sample (having an area of one square inch) under a
pressure of approximately 1.21 kPa (4.9 inches) of water. The
result is expressed in seconds that are frequently referred to as
Gurley Seconds. The reported value represents an average of at
least 12 individual measurements.
Moisture vapor transmission rate. The Moisture vapor transmission
rate (MVTR) is measured according to EN ISO 12572, Hygrothermal
performance of building materials and products, Climate C, 2001.
The measurement is performed using the multilayer method with a
relative humidity of 100% in the cup, and air flow above the sample
of 2.5 m/s and using a measurement interval of 30 minutes. The
resulting MVTR is measured based on the weight loss of water in the
sample The reported value represents and average of at least 1
measurement. Measurements are performed on a Gintronic Gravitest
6400 with an ES 420A balance from MRS Seitter, Lenning-Bruck,
Germany.
Particle penetration. Particle penetration is measured on the TSI
8130 equipment form TSI Incorporated, Shoreview, Minn., United
States. The TSI 8310 is an equipment used for measurement according
to NIOSH Procedures No. RCT-APR-STP-57, 58, 59. For the analysis
the TSI 8130 equipment is used with a sodium chloride particle
generation at a flow rate of 2.3 liter per minute. In order to
achieve a flow rate of 2.3 liter per minute the control valve is
closed and the air flow results from the air through the downstream
photometer only. The sodium chloride particle distribution has a
count median diameter of 0.075 .mu.m, a mass mean diameter of 0.3
.mu.m and a geometrical standard deviation of 1.8. Measurements are
performed with a rise time of 25 seconds and a measurement time of
4 seconds. The penetration is measured based on the difference in
light intensity by an upstream and downstream photometer. The
reported penetration is an average of at least 6 measurements. The
particle penetration can alternatively be expressed as the
logartihmic reduction value based on the following formula: LRV-TSI
8130=-log 10(penetration [%]/100)
Elmendorf tear. Elmendorf tear is measured according to ISO 1974:
1990; Paper--Determination of tearing resistance (Elmendorf
method). The Elmendorf is measured on the 09 ED Tear Tester from
Lorentzen & Wettre, Kista, Sweden. The Elmendorf tear is
measured in both the machine direction (MD) and cross direction
(XD).
Mullenburst strength. Mullenburst strength is measured according to
ISO 2758:2001. Paper--Determination of bursting strength. The
Mullenburst is measured using Lorenzen & Wettre Model 519L from
Lorentzen & Wettre, Kista, Sweden that is integrated into a
Autoline 400 from Lorentzen & Wettre, Kista, Sweden.
Seal strength. Seal strength is measured according to ASTM F88/F88M
Appendix C, with the "free tail" mode. As shown on FIG. 5, 4
stripes per test package 25 are cut at defined location with a
width of 1 inch to test the seal 20. The edges of the stripes are
clean-cut and perpendicular to the direction of the seal. The most
rigid part of the seal was placed on the upper clamp. The nonwoven
sheet produced is the most rigid part of the seal and therefore
placed on the upper clamp. The seals were tested at a grip
separation rate of 300 mm/min. The number of number of measurements
per test item is at least equal to 24. The seal strength is
reported both as the average of the mean load seal strength and as
the average of the peak load seal strength in pound force per inch,
lbf/in.
Dye penetration. Dye Penetration is performed according to ASTM
F1929-12 "Standard Test method for Detecting Seal Leaks in Porous
Mecial packaging by Dye Penetration". ASTM F1929-12 defines a
procedure that will detect and locate a leak equal to or greater
than a channel formed by a 50 .mu.m (0.002 in.) wire in package
edge seals formed between a transparent material and a porous sheet
material. A dye penetrant solution is applied locally to the seal
edge to be tested for leaks. After contact with the dye penetrant
for a specified time of 5 seconds, the package is visually
inspected for dye penetration. Provided no channel is visually seen
the dye penetration test for the package is "passed".
Printing. The nonwoven sheet is printed with a linear barcode or a
2D datamatrix. Testing of linear barcodes is performed according to
ISO 15416, and testing of 2 dimensional datamatrix as described in
ISO 15415.
Fiber tear. Fiber tear is performed by a visual inspection of
packages being opened. The packages were opened manually in the
following manner. The nonwoven sheet is hold in one hand and the
film is hold in the other hand. The time for opening one package is
about one second. The packages are not opened till it reaches the
lower edge seal. In other words, the package is not opened
completely, but only on the top seal and the two seals on the side.
After each package is opened, the surface of the nonwoven sheet
that was sealed to the film is inspected. The surface should be
homogeneous and continuous without the presence for peel off and
tearing of the nonwoven sheet. A package has fiber tear provided
there is peel off or tear of the nonwoven sheet. The above
procedure is performed for at least 50 packages. The percentage of
package showing fiber tear is determined from the number of
packages that show fiber tear divided by the total number of
packages opened. Alternatively, fiber tear can be performed
according to EN 868-5 (2009), Appendix E. However, this standard
does not count some smaller length visual fibers. As shown in the
examples and defined herein, a "package showing fiber tear" is one
that after opening has attached fibers of any length that can been
seen with the un-aided eye.
Examples 1 & 2
Unfinished fibrous nonwoven sheets for further bonding and
embossing were made from a spin solution comprising high density
polyethylene and n-pentane hydrocarbon spin agent, using the
general flash spinning process as described in Examples 9-15 of
U.S. Pat. No. 6,034,008 to Lim et al, with the exception being the
polymer concentration in the spin solution was 17 percent by weight
and the spin temperature was 195.degree. C. The polyethylene had a
melt flow index (as measured by ASTM D1238-13) at 2.16
kg/190.degree. C. of about 0.75 g/10 min. Two different basis
weight nonwoven sheets were made.
The unfinished fibrous nonwoven sheet was then bonded with an
embossed impression pattern by a modification to the process
described in U.S. Pat. No. 5,972,147 to Janis, particularly the
equipment shown in FIG. 2 of that patent. In the process shown in
the figure, the sheet alternately wraps and is preheated by a
single set of two preheating rolls which are followed by bonding of
the sheet in the nips of two sets of two calender rolls wherein the
first set of rolls bonds one side of the sheet and the second set
of rolls bonds the other side of the sheet; followed by cooling the
sheet with a single set of two cooling rolls.
In particular, the process of Janis was modified such that an
additional set of preheating rolls was used, such the sheet
alternately wrapped four preheating rolls (versus 2) without any
nip between the rolls. Further, only the second set of calender
rolls nipped the sheet, operating at a nip pressure of about 200
pounds per linear inch. The first set of calender rolls were left
open and did not nip the sheet. This was followed by cooling the
sheet with a two sets of two cooling rolls (versus a single set of
two).
The particular equipment arrangement involved the bottom of the
sheet wrapping the first preheat roll (PH1), with the top of the
sheet wrapping the second preheat roll (PH2), followed by the
bottom of the sheet wrapping the third preheat roll (PH3), and then
the top of the sheet wrapping the second preheat roll (PH4).
Because the first set of calender rolls does not nip the sheet, the
top surface of the sheet was not embossed. The second set of
calender rolls bonded the bottom surface of the sheet and embossed
a linen impression pattern, such as shown in FIG. 1, in the surface
of the sheet.
The sheet was subsequently transferred to the cooling section and
then wound up into a roll. The temperature of the pre-heat rolls
and embosser are shown in Table 1 and the resulting sheet
properties are summarized in Table 2.
TABLE-US-00001 TABLE 1 Example 1 2 Temperature PH 1 (.degree. F.)
295 295 Temperature PH 2 (.degree. F.) 275 275 Temperature PH 3
(.degree. F.) 275 275 Temperature PH 4 (.degree. F.) 290 290
Embosser 2 temperature (.degree. F.) 290 290
TABLE-US-00002 TABLE 2 Example 1 2 Basis weight (g/m.sup.2) 44 47
Gurley Air Porosity (s) 5.5 7.4 MVTR (g/m.sup.2/24 hr) 7961 9004
Elmendorf Tear MD (N/m) 2.8 3.0 Elmendorf Tear XD (N/m) 3.9 4.5
Elmendorf Tear Avg (N/m) 3.4 3.8 Mullenburst strength (kPa) 571 766
Penetration - TSI 8130 (%) 4.25 2.23 LRV - TSI 8130 1.37 1.65
Comparison Example A
An unfinished fibrous nonwoven sheet for further bonding and
embossing was made from a spin solution comprising high density
polyethylene and n-pentane hydrocarbon spin agent, using the
general flash spinning process as described Examples 9-15 of U.S.
Pat. No. 6,034,008 to Lim et al, with the exception being the
polymer concentration in the spin solution was 17 percent by weight
and the spin temperature was 185.degree. C. The polyethylene had a
melt flow index (as measured by ASTM D1238-13) at 2.16
kg/190.degree. C. of about 0.7 g/10 min.
The unfinished fibrous nonwoven sheet was then bonded by the
process generally as described in U.S. Pat. No. 3,532,589 to David
using a steam pressure of 66.7 psia. This is the process described
in U.S. Pat. No. 6,034,008 to Lim et al. for generating "hard
structure" nonwoven sheets. In this process the nonwoven sheet
passes subsequently over a heated drum, followed by a cooling drum,
then another heating drum and cooling drum to thermally bond both
sides of the material. The heating drum is kept at a temperature
that would result in partial melting of the nonwoven to induce the
bonding of the sheet. The resulting sheet properties are summarized
in Table 3.
TABLE-US-00003 TABLE 3 Example A Basis weight (g/m.sup.2) 44 Gurley
Air Porosity (s) 7 MVTR (g/m.sup.2/24 hr) 8500 Elmendorf Tear MD
(N/m) 4.3 Elmendorf Tear XD (N/m) 4.5 Elmendorf Tear Avg (N/m) 4.4
Mullenburst strength (kPa) 679 Penetration - TSI 8130 (%) 5.0 LRV -
TSI 8130 1.3
Example 3
The resulting nonwoven sheets from Example 1 and Comparison Example
A, each of which had a basis weight of 44 grams/meter.sup.2 were
then is used to create medical packages using Multivac R535
equipment. The Multivac R535 equipment makes 4 packages in one
substrate, each package having a length of 200 mm in machine
direction, about 95 mm in cross direction, and about 7.5 mm seal
width as shown as dimension 5 in FIG. 3. The nonwoven sheet was
attached to the package substrate in the sealing area of contact
using 2 different tie film materials. Film 1 was Multifol GA
Tyvek.RTM., a 100 .mu.m polyimide/polyethylene peelable film from
SUdpack Verpackungen GmbH & Co. KG, Ochsenhausen, Germany. Film
2 was Wipak.RTM. ML E 135 TF PEEL is a
polyethylene/polyamide/polyethylene film from Wipak, Nastola,
Finland.
In all cases the nonwoven surface from the nonwoven sheet of
Example 1 that was bonded and embossed with the linen pattern was
sealed to the film. All packages were made with a seal pressure of
6.5 bar and a dwell time of 1.2 seconds. The sealing temperature
was set to at least two levels for each film--resulting in a
different seal strength. The packages were then opened by peeling
the nonwoven off the tie film.
The seal temperature and resulting seal strength values are given
in the Table 4. With increasing seal temperature, the average peak
seal strength and average mean seal strength increased for the
individual films. Also, at a higher seal strength, the percentage
of packages showing fiber tear increases. However, in every
instance, the nonwoven sheet having the embossed pattern had both
improved fiber tear (peel) and sealing performance, with the
percent reduction in fiber tear ranging from 32% to 73%.
TABLE-US-00004 TABLE 4 Seal Seal Strength Strength Packages Avg.
Avg. Showing Reduction Seal Peak Mean Fiber in Temp Load Load Tear
Fiber Tear Item Film (.degree. C.) (lbf/in) (lbf/in) (%) (%) 1-1 1
105 1.40 0.98 37 34 A-1 1 105 0.41 0.39 56 -- 1-2 1 115 1.41 1.34
35 65 A-2 1 115 0.92 0.91 99 -- 1-3 2 108 0.78 0.72 17 73 A-3 2 108
0.60 0.57 62 -- 1-4 2 118 1.32 1.23 64 32 A-4 2 118 1.15 1.09 94
--
Example 4 and Comparison Example B
Example 2 was repeated using a nonwoven sheet having a basis weight
of 47 g/m.sup.2 with the same embossed linen pattern; however, the
unfinished sheet was bonded using the embossing conditions shown in
Table 5. The resulting bonded nonwoven sheet had a Gurley Porosity
of 3.6 seconds.
For Comparison Example B, the process was repeated with the same
basis weight sheet and temperature conditions as shown in Table 5
but without embossing the bottom of the sheet. (The sheet was not
nipped in the calender rolls.) The resulting nonwoven sheet was
bonded without any embossing and had a Gurley Porosity of 2
seconds.
TABLE-US-00005 TABLE 5 Example 3 B Temperature PH 1 (.degree. F.)
240 240 Temperature PH 2 (.degree. F.) 272 272 Temperature PH 3
(.degree. F.) 280 280 Temperature PH 4 (.degree. F.) 286 286
Embosser 2 temperature (.degree. F.) 296 --
The resulting nonwoven sheet with a surface that was bonded and
embossed with the linen pattern, and the bonded nonwoven sheet
without any embossing was then used to create medical packages
using a Autovak M320 machine, Hongkong, China. The Autovak machine
produced two packages at the same time of about 190 mm length in
machine direction and 127 mm in cross direction, and a 10 mm seal
width as shown by the dimension 10 in FIG. 4. The nonwoven sheet
was attached to the package substrate in the sealing area of
contact using a 135 .mu.m thick polyimide/polyethylene peelable tie
film with code UGBLGV340C from Xiangfu(zhongshan) Film Packaging
Co., LTD, 180, Zhongshan 5th Rd, Guandong, China. The film is
pre-heated in the forming zone. The temperature in the forming zone
is 105.degree. C. and the residence time is set equal to 1.0
second. The seal temperature for all packages is set equal to
120.degree. C. The dwell time is adapted to change the resulting
seal strength of the package. The seal time and seal strength are
shown in Table 6. The packages were then opened by peeling the
nonwoven off the tie film. As shown in Table 6, the packages that
utilized the nonwoven sheet that was only bonded but not embossed
had higher seal strength properties but showed totally unacceptable
fiber tear performance, while the packages utilizing the embossed
nonwoven had acceptable seal strength properties and superior fiber
tear (peel) performance.
TABLE-US-00006 TABLE 6 Seal Seal Strength Strength Packages Sealing
Avg. Peak Avg. Mean Showing Time Load Load Fiber Tear Item (sec)
(lbf/in) (lbf/in) (%) 4-1 1.2 1.43 1.25 8 4-2 1.5 1.53 1.38 2 4-3
1.8 1.67 1.52 0 B-1 1.2 1.42 1.21 100 B-2 1.5 1.57 1.37 100 B-3 1.8
1.77 1.64 100
Examples 5, 6, & 7
These examples illustrate the embossing can be applied to the
nonwoven sheet as a separate step after bonding the nonwoven sheet.
Comparison Example B was repeated, wherein the nonwoven sheet was
bonded but not embossed, using two different nonwoven sheet basis
weights. The bonded sheets were wound up on rolls. The rolls of
bonded nonwoven sheet were then subsequently unwound and embossed
on one surface by nipping the sheet with a set of heated calender
rolls, this time providing one surface of the sheet with an
embossed pattern that was the dogbone pattern as shown in FIG. 2
rather than the linen pattern. The conditions for bonding and
subsequent embossing are shown in Table 7. As in Example 4,
packages were made with the same tie film with the embossed surface
in contact with the tie film. The results shown in Table 8.
TABLE-US-00007 TABLE 7 Example 5 6 7 Basis Weight (g/m.sup.2) 41 47
47 Temperature PH 1 (.degree. F.) 240 240 240 Temperature PH 2
(.degree. F.) 272 272 272 Temperature PH 3 (.degree. F.) 280 280
280 Temperature PH 4 (.degree. F.) 286 286 286 Embosser temperature
(.degree. F.) 296 292 296 Gurley Air Porosity 2.6 4.8 3.2
Penetration - TSI 8130 (%) 5.2 * 6.6 LRV - TSI 8130 1.3 * 1.2 (*
not measured)
TABLE-US-00008 TABLE 8 Seal Seal Strength Strength Packages Sealing
Avg. Peak Avg. Mean Showing Time Load Load Fiber Tear Dye Item
(sec) (lbs/in) (lbs/in) (%) Penetration 5-1 1.2 1.43 1.23 2 Passed
5-2 1.5 1.50 1.33 16 Passed 5-3 1.8 1.65 1.48 24 Passed 6-1 1.2
1.20 1.06 20 Passed 6-2 1.5 1.30 1.20 10 Passed 6-3 1.8 1.44 1.31
12 Passed 7-1 1.2 1.16 1.04 0 Passed 7-2 1.5 1.41 1.29 10 Passed
7-3 1.8 1.54 1.40 22 Passed
The packages were then opened by peeling the nonwoven off the tie
film. As shown in Table 8, the packages that utilizing the embossed
nonwoven had superior peel performance.
Example 8
The nonwoven sheet structures having an embossed impression pattern
that were used in Examples 1 to 7 were tested for barrier and
mechanical properties. All of these inventive sheet structures had
an Elmendorf tear above 2.0N, a Mullenburst strength above 500 kPa.
All of the inventive sheet structures had a particle barrier
penetration of below 10%, using the TSI 8130 equipment operated
with a flow rate of 2.3 L/min. The un-embossed side of each of the
nonwoven structures accepts printing in the form of a linear
barcode and a 2D datamatrix with good visual result.
* * * * *